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Coneccion de Modulos

Date post: 05-Sep-2015
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GM HEI Ignitor for Points For Kawasaki KZ motorcycles (Adaptable to other bikes) By Lou Dudzik 8/06 update 6/10/15 BACK TO HOME General Motors HEI Ignition Module For Points http://home.comcast.net/~loudgpz/GPZweb/Igniti... 1 de 7 27/07/15 11:21
  • GM HEI Ignitor for PointsFor Kawasaki KZ motorcycles

    (Adaptable to other bikes)By Lou Dudzik 8/06 update 6/10/15


    General Motors HEI Ignition Module For Points http://home.comcast.net/~loudgpz/GPZweb/Igniti...

    1 de 7 27/07/15 11:21

  • General Motors HEI Ignition Module For Points http://home.comcast.net/~loudgpz/GPZweb/Igniti...

    2 de 7 27/07/15 11:21

  • UPDATE : It is important to use the correct type of 4-pin HEI modules asthere is now a new type available, which may NOT work for this project.Make sure to use the DR100 type modules, or one from the same family asdescribed in the HEI module notes. Click on the link below for notes on theGM modules and notes on how to determine the correct type is being used.

    Hei Module Notes

    Introduction:This project is to adapt a General Motors High Energy Ignition (HEI) module to provide spark forany Kawasaki KZ motorcycle originally equipped with points. It can also be used on any vehicleincorporating a 12-volt, negative-ground electrical system using a standard Kettering-style ignitionsystem.

    Purpose:The purpose of this project is to use the HEI module in order to reduce wear on the points. It alsoeliminates the need for the condenser and will allow the use of lower resistance ignition coils inorder to get a higher-energy spark at the plugs. It will also allow the elimination of any ballastresistor as long as the ignition coil's primary resistance is 2.4 ohms or higher.

    Overview:This project is designed to work with the stock points and the stock ignition coils. Aftermarket coilscan be used, and any ballast can be eliminated, as long as the coil's primary-side resistance is notless than 2.2 ohms. The 2.2-ohm limit is imposed to prevent the HEI's internal current-limiter frombecoming active. When it is active, more heat is generated inside the HEI module. In the interestof reliability, it is best to avoid unnecessary heat generation in the HEI module.

    One project circuit is required for every ignition coil. Therefore, a 4-cylinder KZ will require twocircuits.

    In order to use an HEI module with points, a small adapter circuit is required between the pointsand the HEI module. The adapter is basically an inverter. The points go from shorted to open inorder trigger a spark. This means the voltage on the point go from 0 to some higher level (low tohigh) when a spark is to occur. The HEI module triggers a spark when the input voltage goes froma higher voltage to a low or negative voltage (high to low). The signal from the points must beinverted to operate the HEI correctly.

    There are 4 versions of the adapter circuit described here. In the accompanying drawing, they arelabeled Fig.1, Fig.2, Fig.3 and Fig.4. Please refer to them in the following descriptions.

    HEI Module:To describe this project, some background should be given about the HEI module. The module has4 terminals plus a heat sink with mounting holes.

    The heat sink and mounting holes are the ground for the module.

    Terminal "B" is the power connection for the module.

    Terminal "C" is the output for the module. It completes the ground path for the ignition coil.Interrupting the ground path causes the coil to generate a spark.

    Terminal "G" is the input to the module. When the voltage at G is higher than about 1.6 volts, the Cterminal is grounded which completes the ignition coil's ground path. When the voltage at G is

    General Motors HEI Ignition Module For Points http://home.comcast.net/~loudgpz/GPZweb/Igniti...

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  • lower than about 1.4 volts, terminal C is open. When C rst opens, the ignition coil produces aspark.

    An HEI module is designed to be controlled by an inductive pickup. Terminal "W" provides acontrol voltage to the pickup. This control voltage extends the dwell to the ignition coil duringhigh-rpm operation. The control voltage will not be used in this project. The dwell-control voltageis overridden by connecting W to the supply voltage.

    However, the W terminal is used for another purpose in the time-out option of this project. Thepurpose of the "time-out" option is to prevent the ignition coil from overheating when the ignitionswitch is turned "on" with the points closed but with the engine not running. It works by switchingo the ignition coil after 5 seconds.

    Basic Circuit (Fig. 1):Fig. 1 is the basic inverter circuit.

    When the W terminal is connected to supply voltage, the G terminal has supply voltage routed to itinternally. Therefore, with nothing connected to G, it defaults to "high". This means C is shortedand the ignition coil has a path to ground. In order to interrupt the coil current at C, G must beforced to go "low", by grounding it.

    In order for the spark to be at the right time, G must be grounded as the points open. This requiresan inverter circuit between the points and the G terminal. R1 and Q1 create an inverter circuit.The points control the inverter circuit. Q1 grounds out the G terminal when the points open.

    There is very little current in the inverter/points circuit so low-power devices will suice for Q1and R1.

    Bypass Option (Fig. 2):Fig. 2 is the basic inverter circuit, with a bypass switch which returns the points back to theiroriginal method of operation. This is only added as a safety feature to provide a "limp-home" modein case the HEI module or inverter-circuit fails. It requires using a standard condenser and a DPDTswitch to re-route the input and output to the points and coil.

    In this system, it would be best to use a 3-ohm or higher coil in order to prevent excessive wear onthe points during bypass operation.

    Points Indicator LED Option (Fig. 3):Fig. 3 is similar to the basic circuit, with the addition of an LED to indicate the status of the points.When the points are closed, the LED is bright. When the points are open, the LED is very dim oro. The LED is lit anytime the coil will be conducting current. This feature is very handy for settingthe ignition timing using the "static" method, and will be an indicator of the coil drawing current incase the motor is stopped while the ignition is left on.

    Points Indicator LED Option (Fig. 3B):Fig. 3B is similar to the circuit in Fig. 3, with LED operating opposite of that in Fig. 3, to indicatethe status of the points. When the points are open, the LED is bright. When the points are closed,the LED is very dim or o. The LED lights up just as the spark would occur. This feature is veryhandy for setting the ignition timing using the "static" method.

    Time-Out Option (Fig. 4):Fig. 4 combines the options of Fig. 2 and Fig. 3 with yet another option; the "time-out" option.

    If the points are closed while the ignition switch is on and the engine is not turning, the ignition

    General Motors HEI Ignition Module For Points http://home.comcast.net/~loudgpz/GPZweb/Igniti...

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  • coil has full current through it. This generates a lot of heat in the coil and some heat in the HEImodule. In order to prevent damage from this condition, a "time-out" option has been devised. Ifthe coil-current is not interrupted by cranking the engine or shutting o the ignition switch, thetime-out option interrupts the coil current automatically after about 5 seconds. Normal operationwill resume as soon as the engine is cranked over. This option is very important and should beincluded if this project is to be a permanent installation on a vehicle.

    The time-out option is implemented through the use of the internal components in the W terminal,though the components were not intended for this use. The W terminal has a very high resistancein series with it. This resistance will be used during the charging of the time-out capacitor C1.

    When the points are open, C1 charges quickly through R1, LED1, R2, and D1. This puts supplyvoltage onto C1 and thus W is also at the supply voltage level. However, the inverter Q1 is shortingout the G terminal so there is no current through the coil.

    When the points close, the voltage at the R2-D1 junction is zero, but D1 prevents C1 fromdischarging quickly. Assuming the engine stops turning so the points stay closed, C1 slowlydischarges through the W terminal's resistance. Meanwhile, G is no longer shorted and "oats" upto a voltage level equivalent to that of W. Therefore, the ignition-coil current is "on". It takes about5 seconds for C1 to discharge to 1.4 volts. G follows W through internal circuitry, so, after 5seconds, the voltage on G is at 1.4 volts and the coil current is interrupted. This produces a singlespark.

    If the points repeatedly open and close quickly, as in normal running, C1 never has time to fullydischarge, but is fully charged every time the points open. In eect, C1 stays charged at supplyvoltage and, thus, W stays at supply voltage. This mimics the operation of the circuits in Figures 1through 3, while the engine is running.

    A few details should be mentioned about the circuit. Because of the design, the rst spark occursonly after the rst time the points are opened to charge C1. This means if the power is turned onwhile the points are closed, there will be no spark the rst time the points open. Only on thesecond opening, and subsequent openings, will there be a spark. This behavior results from thedesign requirements imposed by using a capacitor discharging to produce the time delay. Otherdesigns were tried in which the time delay was generated by the charging of a capacitor. Thisproved problematic, though, because it required the supply voltage to remain steady. This is notpossible because when the coil turns o, the supply voltage inevitably jumps up. This causes avoltage pulse to travel through the charging capacitor, which turns the coil back on. The cyclerepeats and an oscillator is formed. The result is many spark events occur after the initial time-out.The design in Fig. 4 does not have this problem since the capacitor is not aected by supplyvoltage as it discharges. The design in Fig. 4 also used far fewer parts than the other designs.

    Construction:The adapter circuit takes very little power and should work ne even if sealed in silicone sealant.The HEI module will get warm to the touch and should be mounted to an aluminum heat sink. Thesink should be at least 1/8 inch thick for rigidity, and should have at least 6 square inches ofsurface area open to air. The HEI module used for this project was a Wells model DR100. It comeswith heat-sink gel included.

    General Motors HEI Ignition Module For Points http://home.comcast.net/~loudgpz/GPZweb/Igniti...

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  • There are several dierent types of HEI modules. The one used here is the 4-terminal type. Thereare two plastic locator pins on the bottom of the module, which should be cut o in order to mountit ush to a plate. Of course, the plate could just as well be drilled to accept the pins.

    Here is the adapter board for the prototype.

    General Motors HEI Ignition Module For Points http://home.comcast.net/~loudgpz/GPZweb/Igniti...

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  • This is where we slapped the prototype onto a KZ400. It's been about 3 years and you can see themodule has been getting a lot of weather, but is still working great. The LED option is visible andthe circuit components are on the back side of the mounting plate.

    Conclusion:Circuits in Fig.1, Fig.2, Fig.3, and Fig.4, were assembled and hooked up to a test rig to simulate anengine. Each performed very well. The circuit in Fig. 4 was constructed and installed onto aKawasaki KZ400 and has been in use for about 7 years as of May 2014. It's working well and thispage will be updated if any reliability issues arise.


    General Motors HEI Ignition Module For Points http://home.comcast.net/~loudgpz/GPZweb/Igniti...

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